Automatic weighing device



D- l13j 19.38- A. |.=;.v MASON ET AL i 2,139,903

AUTOMATIC WEIGHING` DEVICE f y Filed Jan. 12, i937 2 sheets-sheet z 177@79 Ja L81 6 129.5.

. 57C' 55' /33 J/ZZ 123 L /Nveur-oes ALFRED aw/N masa/v BY Le IP. s/qMmvi ATTORNEY.

lParenteel Dee. 13, 193s lUNITED STATES 2,139,903 AUTOMATICWEIGHINGDEVICE 'y Alfred Edwin Mason and Ira R. Sigman, San Francisco, Calif.

Appiicstion January 12, 1931, serial No. 120,191

4 Claims.

This invention relates to automatic weighing devices and has for itsobjects ,the provision of improved apparatus for quickly and accuratelyweighing batches of material and for successively discharging theweighed material into successively positioned containers', the steps ofdelivering the material for weighing, the weighing, the discharging ofthe weighed material and the properpositioning of the containers andremoval of the filled containers being automatic. An-

.other object is the provision of a photo-electric control arranged forcontrolling the successively repeated cycles of operation of theapparatus. Other objects and advantages will appear in the 1specification and drawings. l

In the drawings, Fig. 1 is a diagrammatic view f of our apparatus.

Fig. 2 is a fragmentary elevational view of the discharge mechanism ofthe weigh hopper. Fig. 3 'is a fragmentary elevational viewof the boxrelease mechanism.

Fig. 4 is a vplan view of the box release mechanism.- i

Fig. 5 is a schematic view of the electrical circuit.

Fig. 6 is a sectional view showing the relation of the two conveyorbelts.

In detail, we provide a main feed hopper or l suitable delivery chute I,positioned tofeed material 2, onto a dribble conveyor 3, and onto'avolume conveyor 4. A deflector plate 5 partially extends across thedribble a portion of the material discharged onto the conveyor 3, onto aldownwardly slanted plate 6, for sliding of the diverted material ontoconveyor 4, which latter conveyor is at a lower elevation than thedribble conveyor. The plate 6 is cut oil at a slant as at 1 along oneedge to insure an even distribution of the material thereover ontoconveyor 4. It is to be noted 40 that the feed chute also feeds materialdirectly onto plate 6, thus the material from the chute is spread outupon passing over plate 6, so as to be distributed fairly evenly on thevolume conveyor 4. `Suitable barriers or flanges 3', 4 are placedalongside the conveyors 3, 4 respectively'to prevent spiili-ng of thematerial over the side edges of the conveyors.

Conveyors 3, 4 are preferably of the beltconveyor type, eachbeingmounted -at opposite 50 ends on suitable, separate pulleys, asindicated. An electric motor 9 is connected to drive dribble conveyor 3in the direction of the arrow and has a conventional magnetic brake IIfor instantly stopping actuation of the motor and conveyor g5 when thecurrent is broken to the motor. vA secv releasable by operation ondelectric motor 8 is connected to drive volume conveyor 4, which motor isalso provided with a magnetic brake I0 to insure stopping of said motorand volume conveyor.

When both conveyors are in operation and 5 material is continuouslybeing fed thereon from the feed chute,` it will be seen that arelatively thin row of material is carried along the dribble conveyorwhile a relatively large amount is carried by the volume conveyor, thelatter conveyor 1o being much wider than the dribble conveyor andadapted to carry all the material that is dropped from the feed chuteexcept that permitted to pass by the end of defiector plate 5 withoutbeing forced onto the slanted plate B. Deilector plate 15 5 ispreferably adjustable so as to vary the quantity that is permitted toremain on conveyor 3, one form of adjustment being a screw 5' threadedlymounted in a stationary bracket 5" the plate being hinged at 6"' toswing back and forth 20 across the path of travel of ythemat'erial onconveyor 3.

In the actual machine conveyors, 3, 4 are spaced laterally at adjacentedges only the width of barrier 3', hence none of the material falling25 over edge 1 of plate 6 will fall between the belts (see Fig. 6). InFig. 1 the belts are shown as beingspaced for purposes of clarity inshowing the various elements.

The material 2such as prunes, for example, 30

passes over the end of conveyor 3 into a stationary hopper I2, and fromconveyor 4 into stationary hopper i3. 'Ihese hoppers I2 and I3 arerespectively provided with gates I4 and I5 at their lower open ends,said gates being hinged at I1 to close the lower ends of the hoppersunder the iniluence of coil springs I3 and I9 and are 'held open bysolenoids I8 and I1 through crank connections I8' and I9'. Torsionspring may, of

course, be substituted for the coil springs. 40 The gates I4 and Ilrespectively, are normally held open by the solenoids I6 and I1 when thedribble and volume feed conveyors are in motion sov that the materialdropping into the hoppers passes by the gates into a weigh hopper 20,which l I weigh hopper is provided with downwardly converging gates 2iand 22 that are hinged at their upper edges to opposite sides of thehopper and meet at their lower edges, thus the engaging ends of thegates form a downwardly pointed apex. The gates are pivotedly connectedfor movement together by a link 23, and are held in closed position by areleasable latch 24, which latch is of a, solenoid 2B connected thereto.The gates are counterweighted u `some installations by applicant havebeen adopted as being preferable.

Below the lower end of the weigh hopper, is a belt or chain conveyor 29comprising spaced parallel runs of belt or chain, preferably the former,supported at opposite ends of parallel shafts 30, 3| suitably pulleys3|', 32', said conveyor being continuously actuated in the direction ofthe arrow by an electric motor 32 or other source of power. The upperrun of the belt may be slidably supported on a table 29' (Fig. 3) so asnot to sag under the weight of containers 33. The containers 33 arecarried by the belt to a point below the discharge gates of the weighhopper.

Between the upper runs of the conveyor is a vertical pivoted stop 34having a roller 34' at its upper end. Said stop is of L shape generallywith .one arm horizontal and the arm 34 carrying the roller, beingvertical. The outer end of the horizontal arm is pivoted at 35 to aninverted stationary channel member 36, and stop 34 with its roller 34'is held in elevated position in the path of the oncoming containerstostop the leading container below the discharge opening of the weighhopper while the belt will continue to slide below the container untilthe stop and roller are withdrawn from engagement withthe forward sideof the container.

'I'he stop 34 is released from stop position by actuation of a solenoid31, the core of which is connected to a member 33 that is horizontallyslidable to and from a position below the stop. When the solenoid isenergized the member l! is pulled from under the stop permitting it tofall and permitting the box or container to ride over the roller. Thusthe stop 34 is not free to rise to block the advance of the nextcontainer on the belt until the container has passed beyond the stop.

Slightly in advance oi' the stop 34 is a pivoted box resetting lever 40that is pivoted at 40' to the channel member said lever extendingupwardly at one end from the pivot 40', and in the direction of travelof the upper run of the belt to a point above the upper surface of thebelt. The lever also extends downwardly at its opposite end to a pointbelow *he horizontal arm of stop 34. A compression spring 40" isinterposed between said opposite en d and stop 34, whereby upon thecontainer engaging the upwardly end of the lever, said upper end will bedepressed, allowing the container to pass thereover, and also placingspring 40 under compression to yieldably-tend to force the .stop 34upwardly. As soon as the rear edge l ofthe rst box clears the stop thetension on the spring immediately will force the stop up-to the to across-bar 4`|", the spring 42.being relatively" space between collars33', or any other suitable spacing means between the containers, to stopthe second or next container below the weigh hopper.

The connection between the solenoid' core and member 3l comprises a pairoi' axially ,aligned springs 4| and 42 with adjacent-ends connectedstii'i.' and connectingbetween said Vbaroni! solenoid core, whileispring4| is relatively light and con:`

nects between the bar and member 33. The spring 42.!unctions as asemi-rigid element, being relatively stiiT, for forcing the member 39back to position below the stop 34 when the solenoid is deenergized, a.conventional coil spring being within the solenoid i'or returning thecore. The light spring 4| acts as a delayed release of the stop due toits resiliency. Carried by cross bar 4I' is a switch 31a that is adaptedto function in an electrical circuit for a purpose later described.

As already stated, the weigh hopper is suspended by any suitable scalebalance supporting means, such as in the Everhard patent, supra, and isarranged to actuate a pointer 45 of a scale dial 4l. The pointer 45carries s. light interceptlng shield adapted to mask the light from alight source 41 oi a photo-electric cell 4l when the material depositedin the weigh hopper closely approaches the desired weight, which maskingfunctions to cause motor 3 andthe volume conveyor to stop and tode-energize solenoid l1 for closing gate I5. Upon the pointer continuingits travel due to the dribble feed of material, the light source will berestored by unmasking the light and this causes the motor I and dribbleconveyor to stop, and to also de-energize solenoid I6 whereby gate I4will close. The point where thelight source is unmasked by the pointernaturally takes into consideration the factors of inertia, time.material in suspension and lag of moving'parts. i 1

It will be noted (Fig. 2) that the latch 24 on the weigh hoppermechanism is pivotally mounted at one end-.and the free end is notchedto engage a projection" on the free end of an arm 3|, which arm issecured at its opposite end to gate 22 for moving therewith about theaxis o'f the gate hinge. When "the gate 22 is closed the projection 50slides into,the notch at the free end of the latch, automaticallylocking the gate closed, latch being pulled downwardly by a spring 24.The core of solenoid 25 is yieldably connected by va spring 24"arrangedtomove the i'ree end of the latch out .of engagement with theprojection 50 when the solenoid is energized, thus permitting the gate22 to open under the weight of material within the weigh hopper, andgate 2| will likewise open with gate 22 and be locked closed by latch 24by reason of theconnecting link 22 that is tioning in said circuit whenclosed upon the closing of the gates to re-start the volume and dribbleconveyors. The gates themselves will automatically close and be lockedin closed position under the iniluence of the counterweights 23, 21 whenthe material in the weigh hopper has been discharged. Y

Assuming the main line switches in the electrical circuit are closed,the sequence ot operation of the apparatus is as follows:

The dribble and volume conveyors deposit the materinlrto be weighedthrough hoppers' |2, I3, the solenoids Il, being energized to hold thehopper gates 4, Il open. and into weigh hopper '23, gates 2|, 22 beinglocked in closedposition by moves sroundtowudthelightbeamoftheuphoto-electric cell assembly. The pointer has been previously set so theshield will cover the ray of light at a point where the weight ofmaterial in the hopper is slightly short oi' the desired weight, and assoon as the shield masks the light ray, an electrical circuit functionsas a, result o! the masking of the light to stop the volume con- Y veyormotor and to set its brakeand the solenoid |1 is de-endergized to permitspring I3 to close the gate of hopper I3 whereby any material that mightbe in suspensionbetween the gate I5 and discharge and of conveyor 4isprevented from falling into the weigh hopper.

The dribble conveyor continues to discharge a relatively small amount ofmaterial into the weigh hopper, thus continuing the movement oi' thepointer 45 and as soon as the shield on the pointer unmasks the lightray, an electrical circuit functions thereupon to stop the dribblemotor, set its brake; to de-energize solenoid I5 whereby gate I4immediately closes; to energize solenoid whereby weigh-hopper gates 2|,22 open and the material in the weigh hopper will fall into container33. Upon the gates closing under the influence of their counterweights,the switch 25a is again closed and solenoid 31 is energized to withdrawstop 33 and to allow the filled container to pass from below thedischarge chute of the weigh hopper and to position the succeeding emptycontainer below said hopper for receiving the subsequently weighed batchof material and the volume and dribble conveyors are started to refillthe weigh hopper for repeating the cycle.

In the schematic view, the solenoids I5, I1, 25 and 31 are similarlynumbered to those described in Fig. 1 and the switch actuated byenergizing and de-energizing 25 is numbered 25a. Likewise the switchesactuated by energizing 31 is numbered 31a. The relay coils in thecircuit are numbered from 53 to 54 inclusive and the switches actuatedby each of the coils upon their being energized and cle-energized bearthe corresponding number of the coil but followed by letters a, b, etc.The explanation will initially describe a two-dump operation of theweigh hoppergates before a removal of the container and will show thesingle dump operation bythe actuation of a switch in the circuit soeither operation as desired may be employed.

In the schematic view, the closing of main switches 8| energizes lines83, 34 and 35 thus lighting bulb 41 through transformer 15 andenergizing photo tube 48 and ampliiier tube 58, the latter comprisinggrid 31 and plate 53. The' sensitive relay coil 53 is thereby energizedand normally open switch 53a is closed while normally closed switch 53his opened. Start button 43 is then closed and current passes from line33 through stop button 12 to lines 85, 31 line 3| switch 55a line 92,relay coil 51 to line 85, thus energizing coil 51. Coil 51 closesswitches 51a, 51h, 51c and 51d, starting dribble motor 8 and releasingbrake I0 and energizing solenoid I3 through lines 83, 84, 85, |24, |22and |25. Current also passes from line 31 through normally closed switch56h, line 35, now closed switch 51d, line 35, relay coil 55 to line 85thus energizing coil 55. Coil 55 closes its own holding in circuit fromline 95 through now closed switch 55a, and line 9D', and switch 55h alsocloses energizing coil 58 through lines 81, 34 and 85 and coil 58 inturn closes switches 53a, 53h and- 58e making circuit 33, 83', |21, |23,84, |25 to 35l thereby releasing brake II, starting volume motor 3 andenergizing rent to pass from line through normally closed switch 25a to83 making a circuit through line 88, switch 53e line 38 to line 85through relay coll 53, energizing coil 53. Normally closed switch 53! isopened upon energizing coil 53 in lines |33, |54

' thus preventing the 4energizing oi relay or solenoid 25 while coil 53is energized.

'The energizing of coil 53 closes switch 53a thereby forming itsholdingin circuit through lines 88, 33', preventing coil 53 fromdropping out when coil 58 is cle-energized. Also normally closed switch53h opens to break circuit 33, 33,

|03, coil 30 to 85 preventing coil 8|li'rorn becoming energized whilecoil 53 is energized and switch sie` 53o is closed making closed circuitIIiI, I 32' and 85 and energizing coil 5I through switches 31a, 52e.Coil 6| in turn forms its own holding in circuit vfrom |0| to |02through closing switch 5Ia. making possible for it to stay energizedwhen coil 53 drops out and switch 6I is also closed to make circuit 83,33 so coil 53 may pick up or become energized when coil 53 drops outlaand switch 59h closes.

As both feed conveyors have been operating the interceptor or pointer 45will have approached the light of the photo-cell hook-up and immediatelyupon its cutting `ofi! the light the coil 53 drops out and switch 53aopens dropping out coil 51. Switch 53h closes thus energizing coil 54through lines 33, 35 and the energizing ci' coil 54 closes switch 54amaking circuit 33, 34 supplylng current to coil 58 through switch 53h,lines 33', 34 and 85. Coil 54 upon being energized also closes switch54h connecting lines 35, 91 and energizing relay coil 55 by way of line35, which coil 55 forms its own holding in circuit by closing switch 55ewhich connects lines 81 and 3i.

The energizing of coil 55 drops out coil 55 by opening switch 58a andswitch 55h then opens to break lines 81, 34making coil 53 take itsenergy by way of lines 33' and 94 through switch 54a.

When coil 51 was dropped out by opening switch 53a through theinterruption of. the light ray, the volume motor stopped, its brake wasset and the volume hopper gate was closed by deenergizing of solenoidI1, but the dribble conveyor continued to feed material into the weighhopper at a low rate of speed and the interceptor continued its traveiacross the light ray. V

When the interceptor uncovers the iight ray the relay coil 53 will againbe energized closing switch 53a. As relay coil 55 has already openedswitch 55a it is seen that coil 51 is not energized by this action. Coil53 also will now open switch 53h thus dropping out relay coils 54, 53.The dropping out of coil 58 results in actuation ci switches 58a to 58!to the position shown in the schematic drawings, thus motor 3 isstopped, its brake set, solenoid I1 is de-energized and gate I5 closes.The desired weight is now in the weigh hopper.

The dropping out of relay coil 58 results in opening switch 53d, thusdropping out coil 55 which results in opening switch 55e and closingswitches 55a and 55h, whereby coil 54 is energized to open switch 54hthus placing the double cutoff control in a pre-first startingcondition.

Bil

Coil 58 will have operated tc open switch 58e and to close switch 58f,when said coil dropped out, and solenoid 25 will be energized throughcurrent passing through a check-Weigh switch 65 and lines Hit, 05 and85. The energizing of solenoid 25 releases the latch 24 (Fig. 1) thusallowing gates 2i, 22 of the weigh hopper to open under the weight ofthe material therein to discharge the material into container 3, landgates 2i, 22 then will automatically close. The opening of the gatesopened switch 25a thus dropping out relay coil 5S and thereby closingswitch 59h and when the gates again close, switch 25o closes wherebyrelay coil 60 is energized through switches Gib, 59113. The energizingof coil 60 closes switch 66a thus connecting lines 8S, 81 and startingthe volume and dribble motors and conveyors.

When coil 5S was dropped out, this resulted in opening switches 53e,59e, the last switch making it impossible for coil 25 to be re-energizeduntil 59e has again closed. Also, coil 6G closed switch 6ththusenergizing coil 62 through normally closed switch 55a and a closedswitch 66a, said coil 62 and switches 64a, 66a, being in circuit 90,His. lit and 85.

The energizing of coil 82 closed switch 62a in circuit Se, EGE' thusenergizing relay coil 63 through closed switches 31, 62a in the circuit89, lS and 85E and also switch 62h in lines 105,101 is opened wherebycoil 64 is prevented from being energized when switch 63a is closed.Coil 62 also acts to open switch 62o, thus dropping out relay coil 6i,which dropping out of coil El results in opening switch Elli anddropping out relay coll Ec. The coil to having accomplished its purposelof re-starting the double cut-off controls, its dropping out results inopening of switch 60h thus dropping out coil 62, but coil 63 remainsenergized by having closed switch 63h which forms its holding in circuitfrom 89 to 85 by i.

way of line SGS, and coil 63 has closed switch 63a thus energizing coilE4 which is in circuit |08 to 35.

Coil EL! forms its own holding in circuit independent o coil 62 byclosing switch 64b in lines IES', 5&1', and the energizing oi coil 64also opened switch Sita thus making it impossible for 62 to again picirup until coil 64 has been dropped out. Also coil t when energized,closes switch 64o in lines 9G, l ll to 85 making possible for solenoidor coil 31 to become energized when coil 6G closes switch Sh.

The second batch of material is now being fed into the same container 3,and when this second batch is discharged the coil 6U will again beenergized through actuation of switch 25a and solenoid or coil 31 willhave energy from line 8G through switches 60h, 64o and line III to line85 and the energizing of coil 31 will open switch 31a'thereby droppingout coils G3, 64, the coil Ell having previously carried on there-starting operation.

From the above it is seen that with the setting` of mechanical switch66a closed, two batches of material must be deposited from the weighhopper before solenoid 31 is energized and the box release stop 34 (Fig.3) is dropped so the container 3 can move forward and re-close switch31a to stop the next container below the weigh hopper. Ii on the otherhand switch 66a were set "open" and mechanical switch 66h mechanicallyconnected thereto were set closed, then coil 62 would not be energizedand switch 60h would close the circuit through switch 66h to solenoid 31allowing the release of container 3 on the iirst discharge. Theoperations described automatically will take place once every 6 or 1seconds when the machine is in operation.

Relative to the photo-electric amplirler in the circuit, when thepotential of the grid 61 of tube 68 changes between certain values, theanode or plate (69) current changes accordingly. The grid potential isobtained from a bridge circuit in which one length is a constantimpedence (condenser and the other leg a variable impedence (photo-tubeI8). When the light shines on tube 48 its impedence decreases, thereforethe voltage across the tube decreases and the amplifier tube gridbecomes less negative. The anode current increases and sensitive relay'53 is energized. When the light decreases, this action is reversed andthe amplifier tube passes less current and sensitive relay drops out. Acondenser 1| is connected across the coil of the sensitive relay 5l tosmooth out the pulsating D. C. The cathode oi' the photo-electricamplifier tube is designated 13, a grid bias adjusting rheostat isdesignated 16 and a grid limiting resistor is designated 11.

With reference to the main control circuit, the switch 65, referred toas a check-weigh switch in the description is inserted in the circuit soas to enable interrupting the sequence of operations so as tc determinethe accuracy of the iinal cut-off, and as already explained, switches56a and 6622 are selector switches to control the discharge of one ortwo loads of weighed material into one container, as desired, before thecontainer is released.

The scale lever actuated by the movement of the weigh hopper isconnected with a conventional dashpot, not shown, to prevent theindicator from traveling too far ahead of the actual weight of vmaterialin the weigh hopper, since the impact of falling material and materialin suspension about to come to rest in said hopper will inuence theweight oi ultimate material deposited therein, and even though theaction of the photo-electric relay is practically instantaneous, thereis a certain lag between the time the impulse is received from thephotocell until the flow of material into the weigh hopper is stopped.All these factors will eilect the speed and accuracy with which materialcan be handled and weighed, and the circuit and arrangement oi' elementsas described are found to give far greater eillciency than heretoforefound in apparatus intended to accomplish generally the same result,insofar as applicants are aware. With the arrangement shown, there is aminimum o! electrical and mechanical actions taking place from the timethe photo-electric cell receives its impulse to the actual stoppage ofmaterial since there are no interposing electrical control actionsbetween the operation of the sensitive relay 53 and relays 51 and 58which control the equipment that actually controls the flow of material.Time lag is thereby practically eliminated. This is extremely importantinasmuch as the dash-pot control is greatly dependent for ultimateeiiiciency upon a minimum time lag, and the greater the lag the greaterthe variation in weightA of successive batches of material dischargedfrom the weigh hopper.

In actual practice, apparatus made according to my invention, will weighfrom 500 to 550 boxes of prunes per hour in lots of pounds of prunes perbox with an average tolerance of plus or minus one-half ounce, the feedto the volume and dribble conveyors being uniform and the prunes beingof /40 grade as compared with ayerage tolerances in excess of 3 ouncesby any other method oi which I am awere. Where raisins are being weighedin 25 pound lots, the average tolerance with my apparatus is even lessthan l@ ounce and the capacity of the apparatus is from about 550 to 60G25 pound boxes per hour.

Having described our invention, We claim:

l. In apparatus of the character described, a volume conveyor and adribble conveyor arranged and adapted to respectively carry .anddischarge a relatively large and relatively. small amount of materialtherefrom, a volume hopper and a dribble hopper respectively arrangedrelative to the conveyors to receive the material discharged from thevolume and dribble conveyors, said volume and dribble hoppers eachprovided With a discharge opening and movable closure therefore, a Weighhopper positioned to receive material from the discharge openings of thevolume and dribble hoppers, the weigh hopper being provided Withadischarge opening and closure therefore, power means arranged forsimultaneously and separately actuating the conveyors, the closures ofthe volume and dribble hoppers being normally open and the weigh hopperclosure being normally closed when both conveyors are actuated to carryanddischarge therefrom, means actuated by thel material weight ofmaterial in the weigh hopper for stopping the volume conveyor and formoving the volume hopper closure to closed position and means actuatedby a predetermined added weight of material in the weigh hopper forstopping the dribble conveyor and for moving the dribble hopper closureto closed position and for opening the weigh hopper closure to dischargethe material therefrom, means arranged to automatically close said weighhopper closure upon discharge of material therefrom, means operated bymovement of the weigh hopper closure for re-starting the conveyors andopening the volume and dribble hopper closures to passage of materialinto the weigh hopper..

2. In apparatus of the character described, a balanced movable Weighhopper, a pair of conveyor belts arranged for feeding material thereto,an electric motor connected to each feed belt respectively forindependently driving each belt, a movable bottom on said weigh hopperfor supporting material fed thereto, separate movable means associatedwith each feed belt between each belt and the-weigh hopper arranged forintercepting material fed from the belt to the hopper, an electricalcircuit, separate electrically actuated means in said circuit connectedto each motor, said movable bottom, and said movable means respectivelyarranged and adapted for actuation by movement of said weigh hopperunder influence of the Weight of material therein for successivelystopping said electric motors and for moving the movable meansassociated with each belt to intercept the material fed therebysimultaneously With the stoppage of the belt, and for moving saidmovable bottom to release the materia] in weigh hopperupon stoppage ofboth motors and for starting the motors, means for moving said movablemeans out of intercepting position actuated by movement of said bottomto material supporting position, and means for mechanically moving saidbottom back to supporting position.

3. In a 4construction as dened in claim 2, said separate electricalmeans including a separate solenoid operatively connected to each ofsaid movable means and bottom.

4. In a construction as dened in claim 2, said separate electrical meansincluding a separate solenoid connected to each of said movable meansadapted to hold said movable means in non-in-

